As Theresa May prepares to trigger Article 50 and take the UK out of the EU, there has been a lot of talk about “the clear will of the people” as expressed through the referendum last year. But as reports emerge about the possible use of big data and social media by both Leave.EU and Vote Leave, we need to ask whether elections run with this kind of tactic can really be said to reflect the free will of the electorate.

The technique known as “behavioural microtargeting” that establishes a psychological profile based on information from social media and uses that profile to feed back targeted political messaging has been variously portrayed as “dystopian”, “business as usual” and “snake oil”. But regardless of how effective it might be or how and where it has been used so far, it does raise new questions that go beyond the privacy debate – if our innermost thoughts can be accessed so easily, what does this mean for freedom of thought?

Freedom of thought is an absolute right protected in international law (Article 18 of the UDHR and the ICCPR and Article 9 of the ECHR). It allows us to think what we like in the inner sanctum of our own mind. There are three key elements that provide protection:

  • a prohibition on coercing someone to reveal their thoughts

  • a prohibition on manipulating a person’s thought

  • a prohibition on penalising someone because of their thoughts.

Crucially, there are no grounds to justify interference with the right. 

It is a right that has had little attention over the years, possibly because of an assumption that the State has no real control over that inner space. But as technology and science continue to develop new ways to engage with our thinking processes and to use them in electoral processes it will be important to consider these new developments in light of the absolute right to freedom of thought. We may only now be beginning to see what interference might look like in practice, but if democracy relies on the will of the people, it is time to start thinking about how we can ensure that the will of the people is free.